The company eventually decided on Jersey, a small island in the English Channel that doesn't tax corporate profits. It's now a crucial part of the estimated $252 billion Apple keeps in an overseas tax structure.

Apple said its restructuring was legal and didn't lower its tax bill. It also noted it has paid more than $35 billion in corporate taxes worldwide over the past three years.

Bringing offshore money back to be taxed in the States is one goal of the GOP tax bill currently in Congress. That bill cuts the corporate tax rate by 15 percent and puts a minimum tax on global profits kept anywhere in the world.